A Lightweight Multi-articular Passive Exoskeleton Using a Single Elastic Band to Improve Crouch Gait Pattern: A Pilot Study.

Abstract

Crouch gait, characterized by excessive flexion of the lower-limb joints, is a common gait disorder among children with cerebral palsy (CP) that compromises mobility and increases energy expenditure. Although surgical and orthotic interventions can improve alignment, maintaining these benefits requires continued postural support and gait practice. While powered exoskeletons have been developed to support upright and coordinated movement, they are often too heavy and complex for practical use. To address this, we developed a lightweight passive exoskeleton that assists the hip, knee, and ankle simultaneously using a single elastic band. The device is designed to provide self-adjusting torque dependent on posture without the need for sensors or active control. It also features user-centric design components to ensure wearability and lightness through a garment-like waist belt and carbon-fiber knee-ankle exoskeleton. We evaluated the biomechanical effects of the exoskeleton in four children with crouch gait (GMFCS levels I-III) by comparing baseline and exoskeleton conditions during overground walking. The preliminary results showed that the exoskeleton tended to increase the mean hip and knee extension angles during the stance phase by 3.5◦ and 3.3◦, respectively, and increased ankle plantarflexion by 1.4◦, indicating the mechanical feasibility of assisting a more extended gait posture. Furthermore, the range of motion of the joints increased by 1.7◦ in the hip, 4.2◦ in the knee, and 8.5◦ in the ankle, suggesting that the passive assistance does not restrict motion and may allow for dynamic joint movement. These preliminary findings suggest the feasibility of passive, multi-joint assistance strategies to facilitate more upright gait patterns in children with crouch gait.